Feasibility of Flow Cytometry Analysis of Gastrointestinal Tract-Residing Lymphocytes in Hematopoietic Stem Cell Transplant Recipients.

The feasibility of lymphocyte isolation and flow cytometry using a single endoscopic biopsy specimen from the gastrointestinal tract of patients who have undergone hematopoietic stem cell transplantation has not been investigated. We acquired 51 endoscopic biopsy specimens from the gastrointestinal tract of 35 patients. We divided the flow cytometry samples into two groups: group A, successful lymphocyte isolation (n=24), and group B, incomplete isolation (n=27). We compared the backgrounds of the samples between the groups to reveal crucial elements in the successful isolation of lymphocytes residing in the gastrointestinal tract. Comparison between the groups revealed lymphocyte isolation success rates differed between biopsy sites. Isolation was most successful in samples from the duodenum (8/9, 88.9%), followed by the ileum (4/8, 50.0%), large intestine (4/11, 36.4%), and stomach (8/23, 34.8%). Tacrolimus was used more frequently in group B (92.6%) than in group A (62.5%) (p=0.015). Logistic regression analysis revealed that isolation from the duodenum or ileum was a significant factor for successful isolation, while tacrolimus use was not statistically significant. In conclusion, the duodenum and ileum are more suitable sites than the stomach and colorectum for acquiring samples for flow cytometry.

Coexpression of natural killer cell antigens by T-cell large granular lymphocytes in hydroa vacciniforme lymphoproliferative disorder and the involvement of Vδ1 + epithelial-type γδT cells.

Hydroa vacciniforme lymphoproliferative disorder (HV-LPD) is a cutaneous variant of chronic active Epstein-Barr virus disease. We examined the coexpression of T- and natural killer (NK)-cell antigens in five patients with classic HV (cHV) and five with systemic HV (sHV). T-cell receptor (TCR) repertoire analysis was performed with high­throughput sequencing. All five cHV patients had increased γδT cells (> 5%), whereas five sHV patients showed γδT- and αßT-cell dominance in two patients each, and a mixture of abnormal γδT and αßT cells in one. Circulating CD3 + T cells expressed CD16/CD56 at 7.8-42.3% and 1.1-9.7% in sHV and cHV, respectively. The percentage of CD16/CD56 + T cells was higher in the large granular lymphocyte or atypical T-cell fractions in sHV, but no TCR Vα24 invariant chain characteristic of NKT cells was detected. Considerable numbers of CD3 + cells expressing CD56 were observed in sHV skin infiltrates. Of the circulating γδT cells tested, TCR Vδ1 + cells characteristic of the epithelial type of γδT cells were dominant in two sHV cases. Thus, atypical αßT and γδT cells in HV-LPD can express NK-cell antigens, such as CD16 and CD56, and Vδ1 + epithelial-type γδT cells are a major cell type in some HV-LPD cases.

Increased CCR4+ and Decreased Central Memory CD4+ T Lymphocytes in the Background Gastric Mucosa of Patients Developing Gastric Cancer After Helicobacter pylori Eradication: An Exploratory Study.

The composition of lymphocytes in the gastric mucosa following the eradication of Helicobacter pylori (H. pylori) in patients with and without gastric cancer has not been compared. This study performed a single spot analysis of gastric mucosal lymphocytes after H. pylori eradication in patients with (n = 13) and without (n = 20) gastric cancer. Our comprehensive analysis of lymphocyte composition in the gastric mucosa revealed that: i) the proportion of CD8+/CD3+ cells was relatively higher in the peri-tumor mucosa than in the background mucosa; ii) the proportion of CCR4+/CD3+ cells was higher, and the ratio of CD62L+/CD3+CD4+ cells was relatively lower in the gastric mucosa of cancer patients than in non-cancer patients; and iii) the proportion of CD45RA-CD62L+/CD3+CD4+ cells, namely, the central memory CD4+ T-cell fraction, was lower in the gastric mucosa of cancer patients than in non-cancer patients. Although the exact mechanism of the altered proportions of CCR4+/CD3+ and central memory CD4+ cells in the gastric mucosa of patients with cancer is unknown, focusing on lymphocytes in the gastric mucosa might help improve our understanding of gastric cancer development after H. pylori eradication.

Site-specific differences in T lymphocyte composition of the gastric mucosa after Helicobacter pylori eradication.

In our earlier work, we revealed that inflammation of the lesser curvature of the gastric body and antrum could constitute independent risk factors for gastric cancer development, while inflammation of the greater curvature was not. The aims of this study were as follows: first, to reveal the differences between T lymphocyte populations of the gastric antrum and the greater and lesser curvatures of the gastric body in patients after Helicobacter pylori eradication; second, to analyze the correlation between the composition of the stomach-resident T lymphocytes and time from H. pylori eradication; and third, to evaluate the sex differences in T lymphocyte subsets after H. pylori eradication. To investigate site-specific differences in stomach-resident T lymphocytes after H. pylori eradication, we performed flow cytometry analysis on samples taken from the gastric antrum, greater curvature of the gastric body, and lesser curvature of the gastric body of 20 patients. We also analyzed the correlation between the composition of the stomach-resident T lymphocytes and the time from H. pylori eradication. The lymphocyte subsets of the antrum and lesser curvature of the body were similar. In contrast, compared to those in the greater curvature of the gastric body, CD4+/CD3+ lymphocyte subsets (43.8 ± 19.4% vs 31.7 ± 14.6%) were elevated in the lesser curvature of the body, whereas CD8+/CD3+ (67.1 ± 21.3% vs 80.4 ± 12.0%), CD7+/CD3+ (91.2 ± 4.6% vs 93.7 ± 3.8%), CCR4+/CD3+ (7.7 ± 8.1% vs 10.4 ± 7.0%), CD45RA+/CD3+CD4+ (27.2 ± 24.8% vs 39.5 ± 20.8%), and CD45RA+/CD3+CD4- (14.2 ± 11.1% vs 18.7 ± 11.5) were lower. Linear regression analysis showed a negative correlation between the time after H. pylori eradication and CD4+/CD3+ (P < .05, R2 = 0.198). There were no significant differences between men and women with respect to the lymphocyte populations. These results indicate that there are site-specific differences in lymphocyte composition in the stomach after H. pylori eradication.

Characterization of Gastric Tissue-Resident T Cells in Autoimmune and Helicobacter pylori-Associated Gastritis.

Data regarding the in-depth surface marker profiles of gastric tissue-resident lymphocytes in autoimmune and Helicobacter pylori-associated gastritis are lacking. In this study, we investigated potential differences in lymphocyte composition between these profiles. We enrolled patients with autoimmune (n = 14), active (current infection of H. pylori in the stomach; n = 10), and inactive gastritis (post-eradication of H. pylori; n = 20). Lymphocytes were isolated from the greater curvature of the stomach and lesser curvature of the body and analyzed using flow cytometry. The CD8+/CD3+ and CD4+/CD3+ ratios differed between the samples. Body CD4+/antrum CD4+, which is calculated by dividing the CD4+/CD3+ ratio in the body by that in the antrum, was significantly higher in autoimmune gastritis (3.54 ± 3.13) than in active (1.47 ± 0.41) and inactive gastritis (1.42 ± 0.77). Antrum CD8+/CD4+ in autoimmune gastritis (7.86 ± 7.23) was also higher than that in active (1.49 ± 0.58) and inactive gastritis (2.84 ± 2.17). The area under the receiver operating characteristic curve of antrum CD8+/CD4+ was 0.842, and the corresponding optimal cutoff point was 4.0, with a sensitivity of 71.4% and a specificity of 93.3%. We propose that an antrum CD8+/CD4+ ratio > 4.0 is a potential diagnostic marker for autoimmune gastritis.

Enriched CD45RA-CD62L+ central memory T and decreased CD3+CD56+ natural killer T lymphocyte subsets in the rectum of ulcerative colitis patients.

OBJECTIVES: To investigate the distinctive features of lymphocytes promoting inflammation in ulcerative colitis. METHODS: We performed flow cytometric analysis of peripheral blood mononuclear cells (PBMCs) and colorectal mucosa lymphocytes in ulcerative colitis patients (n = 13) and control patients (n = 5). RESULTS: CD62L+/CD3+CD4+ (35.7 ± 14.0% vs. 19.9 ± 6.4%) and CD62L+/CD3+CD4- cells (17.1 ± 17.4% vs. 2.4 ± 3.9%) were higher in the rectum of ulcerative colitis patients than in control patients. Subpopulation analysis revealed that CD45RA-CD62L+/CD3+CD4+, that is, central memory T cell fraction in CD4+ T cells, was significantly increased in the rectum of ulcerative colitis, compared to that in control patients (23.3 ± 10.5% vs. 8.2 ± 4.0%). Comparison of rectum and colon samples in ulcerative colitis patients indicated that CD56+/CD3+ was decreased in the rectum compared to that in the colon (11.3 ± 12.5% vs. 21.3 ± 16.5%). The ratio of CD56+/CD3+ was also decreased in the rectum of active ulcerative colitis patients compared to that in ulcerative colitis patients at the endoscopic remission stages (2.8 ± 1.7% vs. 18.5 ± 13.3%). CONCLUSION: We demonstrated that CD62L+ T lymphocytes, particularly the CD45RA-CD62L+ T cell subset that represents central memory T cells, were increased in the rectum of patients with ulcerative colitis. In addition, the CD56+/CD3+ subset (natural killer T cells) was decreased in the rectum compared to that of less inflamed colonic mucosa. These results suggest that the enrichment of central memory T lymphocytes and the reduction of natural killer T cells in the gut mucosa are involved in the pathogenesis of ulcerative colitis.

Analysis of clonality in cutaneous B-cell lymphoma and B-cell pseudolymphoma using skin flow cytometry: Comparison of immunophenotyping and gene rearrangement studies.

To identify clonal neoplastic cells in skin affected by B-cell lymphoma using skin flow cytometry (FCM) techniques, we investigated light-chain restriction using skin FCM with clonality assessed by polymerase chain reaction and light-chain restriction by in situ hybridization (ISH). We retrospectively analyzed 16 cases of B-cell lymphoma with cutaneous involvement: primary cutaneous diffuse large B-cell lymphoma, leg type (pcDLBCL-LT) (n = 7), DLBCL-not otherwise specified (DLBCL-NOS) (n = 6), primary cutaneous follicle center lymphoma (pcFCL) (n = 1), and follicular lymphoma (n = 2), as well as cutaneous B-cell pseudolymphoma (n = 9). Results of skin FCM light-chain restriction analyses were compared with immunoglobulin H (IgH) gene rearrangement and κ/λ ISH findings. Skin FCM detected light-chain restriction in 11 of 14 B-cell lymphoma patients but none of the B-cell pseudolymphoma patients. The sensitivity of skin FCM for distinguishing B-cell lymphoma and B-cell pseudolymphoma was 79%, and the specificity was 100%. Eleven of 13 B-cell lymphoma patients exhibited gene rearrangement (sensitivity 85%), whereas six of seven pseudolymphoma patients were negative (specificity 86%). ISH was positive in three of 16 B-cell lymphoma cases (sensitivity 19%) but none of the B-cell pseudolymphoma cases (specificity 100%). ISH sensitivity was 29% for pcDLBCL-LT, 17% for DLBCL-NOS, and 0% for pcFCL and follicular lymphoma. Skin FCM therefore appears to be more sensitive than ISH in detecting light-chain restriction in DLBCL and follicular lymphoma, and as sensitive as IgH gene rearrangement analysis in detecting clonality. Skin FCM is thus a promising diagnostic tool for identifying monoclonal neoplastic B-cell populations.

Isolation of lymphocytes from the human gastric mucosa.

Flow cytometry is widely used for lymphocyte immunophenotyping in clinical settings. However, few studies have applied it for analyzing lymphocytes of the gastric mucosa. This review offers an overview of methodologies for isolating lymphocytes from the human stomach. Previously reported articles were reviewed, focusing on procedures for isolating human gastric mucosal lymphocytes. Helicobacter pylori-associated peptic diseases and gastric cancer are two major subjects of research in this field. Enzymatic dissociation, mechanical dissociation, or a combination of the two have been used to isolate lymphocytes from the stomach. Intra-epithelial and lamina propria lymphocytes were separately isolated in several studies. We also summarize the history and present trends in analyzing lymphocytes in patients with gastric disease.

Technique for single-step lymphocyte isolation from an endoscopic biopsy specimen for the diagnosis of gastrointestinal lymphoma.

In this paper, we introduce a simplified, one-step procedure for lymphocyte isolation from an endoscopically biopsied fragment. For lymphocyte isolation, an endoscopically harvested specimen and 5 mL of normal saline solution were placed in a wire mesh strainer set in a porcelain bowl. To obtain the lymphocyte suspension, the solid specimen was crushed using the rubber portion of a plunger of a 10 mL injection syringe. Flow cytometry was performed using the lymphocyte suspension. For validating our methods, the one-step lymphocyte isolation technique was used to perform flow cytometry on samples from 23 patients with (n = 12) or without (n = 11) gastrointestinal lymphoma. Flow cytometry of light chain expression was performed in all patient samples (feasibility: 100%). Sensitivity was 83.3% (10/12) and specificity was 100% (11/11). In conclusion, lymphocytes isolated from a single endoscopic biopsy specimen using our simplified and quick procedure are suitable for flow cytometry. Considering that flow cytometry has an important advantage of providing the results on the examination day itself, the results of this study suggest that flow cytometric analysis using our single-step lymphocyte isolation technique can be potentially used to diagnose lymphoma in the gastrointestinal mucosa. •We introduce a simplified, one-step procedure for lymphocyte isolation from an endoscopically biopsied fragment.•Our technique is feasible for flow cytometric analysis in patients with gastrointestinal lymphoma as well as those with gastrointestinal lesions that are suspected to be lymphoma.

Appendiceal Orifice Inflammation in Ulcerative Colitis Mimicking Mucosa-Associated Lymphoid Tissue Lymphoma in the Cecum.

A 55-year-old Japanese woman, who had been diagnosed with ulcerative colitis at 18 years of age, underwent screening endoscopy examinations. Esophagogastroduodenoscopy revealed an extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) of the stomach. Colonoscopy showed a slightly elevated reddish lesion with dilated microvessels but no erosions or ulcers. Although MALT lymphoma in the cecum was endoscopically suspected, flow cytometry and pathological analyses led to the diagnosis of appendiceal orifice inflammation in ulcerative colitis. This case highlights the diversity of the endoscopic appearance of appendiceal orifice inflammation in ulcerative colitis.

An Endoscopic Biopsy Specimen Contains Adequate Lymphocytes for Flow Cytometric Analysis of Light Chain Expression in the Gastrointestinal Mucosa.

OBJECTIVE: Flow cytometry has not been widely used in routine clinical practice for the diagnosis of gastrointestinal lymphoma; this is mainly because of the absence of an appropriate protocol. Here, we established a protocol for flow cytometric analysis of a single biopsy specimen from the gastrointestinal mucosa and investigated its sensitivity and specificity. DESIGN: In this prospective study, we enrolled patients with previously diagnosed gastrointestinal lymphoma and patients with gastrointestinal lesions that were suspected to be lymphoma. RESULTS: Overall, 15 patients with gastric extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (N=8), duodenal follicular lymphoma (grade 1; N=5), and benign lymphoid hyperplasia (ileum, N=1, and rectum, N=1) were included in this study. Of these, lymphocytes were isolated from 14 patients (93.3%). There were 200,000-1,500,000 viable cells per patient. Biopsy specimens from 10 out of the 12 patients with lymphoma were positive for light chain restriction; the two patients with benign lymphoid hyperplasia showed negative results. CONCLUSIONS: An adequate number of lymphocytes for flow cytometry could be isolated from a single specimen of endoscopic mucosal biopsy from 93.3% of the patients. Overall, the sensitivity of flow cytometric analysis of light chain expression for the diagnosis of B-cell lymphoma was 83.3%, and the specificity was 100%. Although further investigation is required as the sample size of the present study was small, our study suggests a potential option for diagnosing B-cell lymphoma in the gastrointestinal mucosa.

Intestinal Diffuse Large B-Cell Lymphoma in a Patient with Systemic Lupus Erythematosus.

A 44-year-old Japanese woman with systemic lupus erythematosus (SLE) presented to our hospital with abdominal pain. Radiological and endoscopic examinations led to the diagnosis of diffuse large B-cell lymphoma of the jejunum, which was subsequently resected. Patients with SLE reportedly have an increased risk of non-Hodgkin lymphoma, as demonstrated by our patient. Hence, lymphoma should be considered in the differential diagnosis of neoplastic lesions emerging in SLE patients. In addition, flow cytometry using endoscopically biopsied fragments is useful for the immediate diagnosis of lymphoma, leading to timely and accurate preoperative staging.

Persistent hypogammaglobulinemia due to immunoglobulin class switch impairment by peri-transplant rituximab therapy.

Post-transplant lymphoproliferative disorder (PTLD) is one of the most serious complications of allogeneic hematopoietic stem cell transplantation (HSCT). Rituximab is effective for PTLD; however, rituximab can produce adverse effects, including hypogammaglobulinemia. Here, we present the case of an 18-year-old female with refractory cytopenia of childhood who developed persistent selective hypogammaglobulinemia with low immunoglobulin G (IgG) 2 and IgG4 levels and monoclonal protein after rituximab therapy against probable PTLD. Despite B-cell recovery, the serum IgG levels gradually declined, reaching < 300 mg/dL at 33 months after rituximab treatment. In addition, class-switched memory (CD27 + IgD -) B cells were limited in phenotypic analysis. These findings suggest that peri-HSCT rituximab may contribute to an abnormal B-cell repertoire induced by impaired immunoglobulin class switch.

The expression of cell adhesion molecule 1 and its splicing variants in Sézary cells and cell lines from cutaneous T-cell lymphoma.

Cell adhesion molecule 1 (CADM1) is aberrantly expressed by T-cell neoplasms such as adult T-cell leukemia/lymphoma (ATLL) and mycosis fungoides (MF). We studied the expression of CADM1 and its splicing variants in Sézary syndrome (SS), MF, other cutaneous T-cell lymphoma (CTCL), and cell lines derived from T- and B-cell lymphomas. Soluble CADM1 was measured in the patients' sera. CADM1+ cells in the blood and skin lesions were examined by flow cytometry and immunostaining, respectively. Soluble CADM1 was measured by ELISA, and the splicing variants of CADM1 transcripts were determined by reverse transcriptase-polymerase chain reaction, followed by sequencing. As a result, circulating CADM1+ cells were significantly increased in seven out of 10 patients with SS, ranging from 7.9% to 74.5% of the CD3+CD4+ fractions (median 33.7%; cut-off value 6.5%). The percentages of CADM1+ cells were usually less than those of circulating Sézary cells. CADM1 was expressed, to various degrees, in six of nine T-cell lines derived from SS, MF, ATLL, and anaplastic large cell lymphoma (ALCL), but negative in B-cell lymphoma-derived cell lines. CADM1+ cells were present in the skin infiltrates of MF, SS, ATLL and ALCL. Serum levels of soluble CADM1 were not significantly elevated in SS/MF. Three major splicing variants of CADM1 expressed by neoplastic T-cells contained different combinations of the exons 7, 8, 9 and 11, including a putative oncogenic variant composed of exons 7-8-9-11. In conclusion, CADM1 is frequently expressed in Sézary cells and cell lines from CTCL.

Feasibility of flow cytometric analysis of restricted light chain in endoscopic biopsy specimens from patients with gastrointestinal tract B cell lymphoma: a pilot study.

OBJECTIVE: Gastrointestinal tract lymphomas are currently detected more frequently due to advances in endoscopic technology. The aim of this study was to assess the feasibility of flow cytometric analysis of restricted light chain in endoscopic biopsy specimens for the diagnosis of gastrointestinal tract B-cell lymphoma. We prepared viable cell suspensions from unfixed specimens obtained from 10 consecutive patients who had a previous histological diagnosis of gastrointestinal tract B-cell lymphoma. We performed immunophenotypic studies with multi-color flow cytometry and assessed clonality through examination of immunoglobulin light chain expression exclusively in a population identified by anti-CD45 or CD20 antibodies. RESULTS: We could perform light chain expression analysis with 2 endoscopic biopsy specimens from all 10 patients with gastrointestinal tract B-cell lymphoma. We conclude that flow cytometric analysis of endoscopic biopsy specimens is feasible and thus likely useful for the diagnosis of gastrointestinal tract B-cell lymphoma in clinical settings. Trial registration UMIN Clinical Trials Registry, UMIN000027730. Registered 12 June 2017.

Panel-based next-generation sequencing identifies prognostic and actionable genes in childhood acute lymphoblastic leukemia and is suitable for clinical sequencing.

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Although the cure rate of ALL has greatly improved, a considerable number of patients suffer from relapse of leukemia. Therefore, ALL remains the leading cause of death from cancer during childhood. To improve the cure rate of these patients, precisely detecting patients with high risk of relapse and incorporating new targeted therapies are urgently needed. This study investigated inexpensive, rapid, next-generation sequencing of more than 150 cancer-related genes for matched diagnostic, remission, and relapse samples of 17 patients (3 months to 15 years old) with relapsed ALL. In this analysis, we identified 16 single-nucleotide variants (SNVs) and insertion/deletion variants and 19 copy number variants (CNVs) at diagnosis and 28 SNVs and insertion/deletion variants and 22 CNVs at relapse. With these genetic alterations, we could detect several B cell precursor ALL patients with high-risk gene alterations who were not stratified into the highest-risk group (5/8, 62.5%). We also detected potentially actionable genetic variants in about half of the patients (8/17, 47.1%). Among them, we found that one patient harbored germline TP53 mutation as a secondary finding. This inexpensive, rapid method can be immediately applied as clinical sequencing and could lead to better management of these patients and potential improvement in the survival rate in childhood ALL.

Papuloerythroderma-like cutaneous involvement of a CD62L- subclone of T-cell prolymphocytic leukemia.

We report the case of an 88-year-old Japanese man with erythrodermic involvement of T-cell prolymphocytic leukemia (T-PLL). He had a history of pharyngeal diffuse large B-cell lymphoma successfully treated with polychemotherapy including cyclophosphamide and epirubicin, 6 years before the current illness. He presented with numerous reddish, coalescing, flat-topped papules on the trunk and extremities, sparing the skin folds of the abdomen, the features of which mimicked those of papuloerythroderma. Immunohistochemistry showed perivascular and epidermotropic infiltration of CD3+ CD4+ T cells in the cutaneous lesion. However, flow cytometric analysis revealed that the skin infiltrating T cells were negative for surface CD4, and that CD3+ CD4- CD8- cells made up 92% of the T-cell fraction of peripheral blood. The circulating atypical T cells had a round or oval nucleus and prominent nucleoli, and the deletion of chromosomes 6q, 13 and 17. These cytological profiles were consistent with those of T-PLL and distinct from those of Sézary cells. The same T-cell clone was detected in the cutaneous lesion and peripheral blood, but the expression of CD62L was absent in the skin infiltrates and present in the circulating cells. No specific mutation was detected in STAT3 or STAT5B. Although low-dose oral etoposide had a beneficial effect on the skin rash, a fatal crisis of marked leukocytosis (169 × 103 /µL) occurred 19 months after the illness onset. CD62L-leukemic cells of T-PLL may infiltrate the skin to form papuloerythroderma-like cutaneous lesions.

Positive Minimal Residual Disease of FLT3-ITD before Hematopoietic Stem Cell Transplantation Resulted in a Poor Prognosis of an Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) patients with fms-related tyrosine kinase 3 (FLT3)-internal tandem duplication (ITD) often have a poor prognosis, even after hematopoietic stem cell transplantation (HSCT). We report a case of AML with FLT3-ITD identified upon initial diagnosis, who received HSCT at complete remission after 3 consecutive chemotherapies. However, the patient relapsed when the same FLT3-ITD clone emerged, and finally died. Retrospective analysis revealed an allelic ratio of FLT3-ITD/wild type of 1.1 and 0.0096 upon initial diagnosis and before HSCT, respectively. The detection of any minimal residual FLT3-ITD clone before HSCT is useful in the treatment of AML with FLT3-ITD.

Relapsed childhood acute myeloid leukemia patient with inversion of chromosome 16 harboring a low FLT3 internal tandem duplication allelic burden and KIT mutations.

Inversion of chromosome 16 [inv(16)] has a good prognosis in acute myeloid leukemia (AML), but additional genetic aberrations influence the outcome. We herein describe the case of a 15-year-old Japanese boy with inv(16) harboring a low-allelic burden internal tandem duplication of FLT3 (FLT3-ITD) and KIT mutations. Conventional chemotherapy eradicated a clone with a low-allelic burden FLT3-ITD mutation, although another clone with a KIT mutation occurred 17 months later. Further investigation is necessary to identify AML with inv(16) conferring poor prognosis, to facilitate appropriate treatment with additional drugs, such as dasatinib or gemtuzumab ozogamicin.

Transient myeloproliferative disorder with partial trisomy 21.

Myeloid malignancy with Down syndrome (ML-DS) is estimated to have a step-wise leukemogenesis including GATA1 mutation. Trisomy 21 is essential for ML-DS; however, we do not know exactly which gene or genes located on chromosome 21 are necessary for the ML-DS. We report a female infant with transient myeloproliferative disorder (TMD) and partial trisomy 21. SNP array analysis showed 10 Mb amplification of 21q22.12-21q22.3, which included DYRK1A, ERG, and ETS but not the RUNX1 gene. With two other reported TMD cases having partial trisomy 21, DYRK1A, ERG, and ETS were the most likely genes involved in collaboration with the GATA1 mutation.